One important application of micro-fluidics is to make small, automatic measurement instruments, to replace the function of large laboratory instruments that require highly trained and skilled operators. The micro-instrument must precisely meter the sample and reagents required for the analysis, and then thoroughly mix them in preparation for analysis of a very small quantity of material. One significant advantage of the small sample is that both dispersion times and chemical reaction times can be much shorter.
Many researchers have developed techniques to control the flow in micro-circuits. Some related mechanical methods use shape memory metal alloys as actuators, or piezoelectric actuation or voice coils.
Other known micropump technologies include various techniques adapted from MEMs fabrication and other unidimensional techniques. These include: Shape memory alloy micropump—Two TiNi, a material that when heated deflects in a certain direction; actuators are bonded together in opposite orientation. When one is heated up the TiNi actuator deflects downward, when the other is heated while the first one cools the actuator deflects upward. Thermally cycling the two TiNi actuators 180° out of phase will cause the actuator to move up and down continuously.
Valve-less diffuser pump—a single pump chamber and piezoelectric actuation, uses diffusers as flow directing elements that are connected to the pump chamber with an oscillating diaphragm.
Injection molded—uses the conventional construction of a loud speaker where a flexible membrane is moved by an electromagnetic actuator that consists of a magnet that sits in a coil.
Bubble pump—relies on the formation of a vapor bubble in a channel. Uses the surface tension of water to push the fluid through a microchannel.
What is needed, therefore, are techniques for providing a valve and pump suitable for micro-fluidic applications.